Regions
Northwest Coastal.
Get out and enjoy the good riding conditions for Christmas before conditions change dramatically with the arrival of a powerful storm this weekend.
Weather Forecast
We're looking at a brief clearing on Christmas before a powerful storm hits the north coast. Snow should start falling overnight on Friday. Coastal regions will see up to 30cm by Saturday evening, another 20cm overnight, with intense snowfall continuing into Monday resulting in total forecast storm amounts of up to 60cm. Terrace will see slightly less, with 20cm expected Saturday and 50cm through the storm. An artic front just inland will keep thing cool and freezing levels are expected to stay below 500m. Strong to extreme south west winds are going to hit the coast on Saturday morning and will persists through the forecast period.
Avalanche Summary
No recent avalanche have been reported.
Snowpack Summary
Cool temperatures have been encouraging faceting in the upper snowpack, breaking down any storm slab that previously existed. Winds have been light and variable for the last week although reports from the field indicate there is lingering wind effect in the alpine or at tree-line. 25-40 cm of low density snow sitting above the December 17th surface hoar, and 35-55 cm above the December 14th surface hoar. Snow pit tests earlier in the weak produced sudden failures on both of these layers, however, it sounds like the overlying slab properties have subsequently changed. The December 1st surface hoar is now down a meter or so however, distribution and sensitivity of this layer is variable. In some areas, it may still be sensitive to human triggering and capable of wide propagations, in other areas it is non-existent or has gained significant strength.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.